Method for Wireless Communication in A Device with Co-Existence Radio

ABSTRACT

Various methods for wireless communication in a device with co-existed/co-located radios are provided. Multiple communication radio transceivers are coexisted/co-located in a user equipment (UE) having in-device coexistence (IDC) capability, which may result in IDC interference. For example, the UE is equipped with both LTE radio and some ISM band applications such as WiFi and Bluetooth modules. In a first method, the network identifies IDC capability by UE identification (e.g., UE ID). In a second method, the UE intentionally performs cell selection or reselection to cells in non-ISM frequency bands. In a third method, the UE signals the existence of ISM band applications via capability negotiation. In a fourth method, the UE signals the activation of ISM band applications by signaling messages (e.g., RRC message or MAC CE). Under the various methods, the UE and its serving eNB can apply FDM or TDM solutions to mitigate the IDC interference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation, and claims priority under 35 U.S.C.§120 from nonprovisional U.S. patent application Ser. No. 13/135,844,entitled “Method for Wireless Communication in a Device withCo-existence Radio,” filed on Jul. 15, 2011, the subject matter of whichis incorporated herein by reference. application Ser. No. 13/135,844, inturn, claims priority under 35 U.S.C. §119 from U.S. ProvisionalApplication No. 61/366,819, entitled “Method for wireless communicationin a device with co-existence radio,” filed on Jul. 22, 2010; U.S.Provisional Application No. 61/390,531, entitled “RRM Solutions forIn-Device Coexistence,” filed on Oct. 6, 2010, the subject matter ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless networkcommunications, and, more particularly, to wireless communication in adevice with co-existence radio interfaces.

BACKGROUND

Ubiquitous network access has been almost realized today. From networkinfrastructure point of view, different networks belong to differentlayers (e.g., distribution layer, cellular layer, hot spot layer,personal network layer, and fixed/wired layer) that provide differentlevels of coverage and connectivity to users. Because the coverage of aspecific network may not be available everywhere, and because differentnetworks may be optimized for different services, it is thus desirablethat user devices support multiple radio access networks on the samedevice platform. As the demand for wireless communication continues toincrease, wireless communication devices such as cellular telephones,personal digital assistants (PDAs), smart handheld devices, laptopcomputers, tablet computers, etc., are increasingly being equipped withmultiple radio transceivers. A multiple radio terminal (MRT) maysimultaneously include a Long-Term Evolution (LTE) or LTE-Advanced(LTE-A) radio, a Wireless Local Area Network (WLAN, e.g., WiFi) accessradio, a Bluetooth (BT) radio, and a Global Navigation Satellite System(GNSS) radio. In the MRT, the LTE-A radio is an Orthogonal FrequencyDivision Multiple Access-based (OFDMA-based) mobile broadband technologythat is capable of providing global roaming services, and the WiFi radiois capable of providing huge bandwidth transmission via local access.The combination of LTE-A and WiFi radio is one of the examples of WiFioffloading, which is a common paradigm of future communications.Multiple radios co-located or coexisted in the same communication deviceis also referred to as in-device coexistence (IDC).

Due to spectrum regulation, different technologies may operate inoverlapping or adjacent radio spectrums. For example, LTE/LTE-A TDD modeoften operates at 2.3-2.4 GHz, WiFi often operates at 2.400-2.483.5 GHz,and BT often operates at 2.402-2.480 GHz. Simultaneous operation ofmultiple radios co-located/coexisted on the same physical device,therefore, can suffer significant degradation including significantcoexistence interference (e.g., in-device interference) between thembecause of the overlapping or adjacent radio spectrums. Due to physicalproximity and radio power leakage, when the transmission of data for afirst radio transceiver overlaps with the reception of data for a secondradio transceiver in time domain, the second radio transceiver receptioncan suffer due to interference from the transmission of the first radiotransceiver. Likewise, data transmission of the second radio transceivercan interfere with data reception of the first radio transceiver.

In LTE/LTE-A systems, there are several available radio resourcemanagement (RRM) technologies to mitigate interference. Two radioresource control (RRC) states are defined for LTE UEs. One isRRC_CONNECTED state indicating that a UE is active and the other one isRRC_IDLE state indicating that a UE is idle. In one RRM scheme, whenradio link failure (RLF) is declared, a user equipment (UE) may reselectto a cell in another frequency band. Another possible RRM scheme is thatthe UE may report measurement results (e.g., poor reference signalreceived power or reference signal received quality (RSRP/RSRQ) of aserving cell) to its serving base station (eNB). Furthermore, formobility management, if a UE is active (e.g., RRC_CONNECTED state), thenthe network either refrains from handovering the UE to frequencies/bandswith interference or handovering the UE to a cell with better signalmeasurement. If a UE is idle (e.g., RRC_IDLE state), then the UE avoidscamping on frequency/bands with significant interference.

The current Rel-8/9 LTE RRM design, however, does not consider theeffect of IDC interference. If an ongoing LTE communication is severelyaffected by IDC, RLF will occur. However, it normally takes one secondor longer for a UE to declare RLF, which results in long response time.Another issue is that, under the current RRM design, a UE may handoverback to a cell in the original frequency band later, which results inping-pong effect. In addition, Rel-8/9 backward compatibility should beconsidered when designing RRM that addresses the IDC interferenceproblem.

SUMMARY

Various methods for wireless communication in a device withco-existing/co-locating radios are provided. Multiple communicationradio transceivers are coexisted/co-located in a user equipment (UE)having in-device coexistence (IDC) capability, which may result incoexistence interference. For example, the UE is equipped with both anOFDMA-based radio such as an LTE radio transceiver and some ISM bandapplications such as WiFi and Bluetooth modules. The WiFi or BT deviceis also referred to as an ID device that may introduce significant IDCinterference because the coexisted/co-located radio transceivers operatein overlapping or adjacent frequency channels. Under the variousmethods, the UE and its serving eNB can apply FDM or TDM solutions tomitigate the IDC interference.

In a first method, the network identifies IDC capability by UEidentification (i.e., UE ID). In one embodiment, the operator allocatesa specific set of UE IDs (e.g., IMEI-SV) to multi-radio coexisted UEs.By detecting the specific UE ID, the serving eNB may refrain fromhanding over a UE with IDC capability to cells in ISM or near-ISM bandswhen the UE stays in RRC_CONNECTED state. On the other hand, when the UEgoes to RRC_IDLE state from RRC_CONNECTED state, the eNB may prioritizenon-ISM bands via RRCConnectionRelease message with redirectionparameters. Identifying IDC capability by UE ID is a core network(CN)-centric solution, and is a backward compatible solution for LTERel-8/9 eNBs and UEs. It is also transparent to UEs.

In a second method, the UE intentionally performs cell selection orreselection to cells in non-ISM frequency bands. In RRC_IDLE state, theUE tries to select or reselect to cells in non-ISM frequencies byintentionally de-prioritizing the ISM frequencies. In RRC_CONNECTEDstate, the UE first switches to RRC IDLE state, and then tries toperform the cell selection or reselection. Deprioritizing ISMfrequencies for cell selection or reselection is a UE-centric solution.It is only relevant to UE internal operation and the network is unawareof the ISM operation in the UE. Since this is a UE-oriented cellselection/reselection, this solution could be applied to LTE Rel-8/9eNBs/UEs.

In a third method, the UE signals the existence of ISM band applicationsvia capability negotiation (i.e., static reporting). In a firstembodiment, a new parameter for indicating the existence of the IDdevice is added in UE capability message. The first embodiment is notbackward compatible because a new ASN.1 code-point is needed to supportthe new parameter. In a second embodiment, the UE capability messageincludes the supported frequency bands of the UE, and the existence ofthe ID device is implicitly indicated by the changing of the supportedfrequency bands (e.g., via a track area update (TAU) procedure). Thesecond embodiment is backward compatible and can be applied in LTERel-8/9.

In a fourth method, the UE signals the activation of ISM bandapplications by signaling messages, such as RRC message or MAC controlelement (CE). In general, the UE can update the activation/deactivationof its ID device (i.e., semi-static reporting) or report the measurementresults of the frequencies that may be affected by the ID device (i.e.,dynamic reporting). More specifically, the UE can report IDC informationrepresented in the form of RRC massage or MAC CE, and the carriedinformation of the signaling message can be measurements based on eNBconfiguration including additional measurement report for ISM radios.Based on the reported information, the eNB can handover UE to cells inthe non-ISM frequencies (FDM solution) or schedule LTE transmission intime domain with care (TDM solution).

In one advantageous aspect, when the serving eNB handovers the UE to atarget eNB over a non-ISM frequency band to mitigate IDC interference,the target eNB refrains from handing over the UE back to ISM frequencyband to avoid ping-pong effect. A first type of eNB-centric solution(e.g., information forwarding from the source eNB to the target eNB viaX2 interface) and a second type of UE-centric solution (e.g., indicatingIDC failure error cause) are provided to avoid ping-pong effect.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 illustrates a user equipment (UE) having coexisting radio devicesin a wireless communication system in accordance with one novel aspect.

FIG. 2 is a flow chart of a method of performing cellselection/reselection in RRC IDLE state in accordance with one novelaspect.

FIG. 3 is a flow chart of a method of signaling in-device coexistence(IDC) from UE perspective in accordance with one novel aspect.

FIG. 4 is a flow chart of a method of signaling in-device coexistence(IDC) from eNB perspective in accordance with one novel aspect.

FIG. 5 illustrates a method of statically signaling in-devicecoexistence (IDC) via capability negotiation.

FIG. 6 illustrates a first embodiment of dynamically signaling IDC andISM band application via measurement configuration of an existing event.

FIG. 7 illustrates a second embodiment of dynamically signaling ISM andapplication via measurement configuration of a new IDC event.

FIG. 8 illustrates a method of MAC CE-based IDC indication forsemi-static reporting.

FIG. 9 illustrates one embodiment of eNB-centric solution for avoidingping-pong effect.

FIG. 10 illustrates one embodiment of UE-centric solution for avoidingping-pong effect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 illustrates a user equipment (UE) having coexisting radio devicesin a wireless communication system 100 in accordance with one novelaspect. Wireless communication system 100 comprises a serving basestation (e.g., evolved node-B) eNB 101, a first user equipment UE 102, asecond user equipment UE 103, a WiFi access point WiFi AP 104, aBluetooth device BT 105, and a global positioning system satellitedevice GPS 106. Wireless communication system 100 provides variousnetwork access services for UE 102 and UE 103 via different radio accesstechnologies. For example, eNB 101 provides OFDMA-based cellular radionetwork (e.g., a 3GPP Long-Term Evolution (LTE) or LTE-Advanced (LTE-A)system) access, WiFi AP 104 provides local coverage in Wireless LocalArea Network (WLAN) access, BT 105 provides short-range personal networkcommunication, and GPS 106 provides global access as part of a GlobalNavigation Satellite System (GNSS). To better facilitate the variousradio access technologies, UE 102 is a multi-radio terminal (MRT) thatis equipped with multiple radios coexisted/co-located in the same deviceplatform (i.e., in-device). On the other hand, UE 103 is only equippedwith an LTE radio transceiver for LTE communications.

Due to spectrum regulation, different radio access technologies mayoperate in overlapping or adjacent radio spectrums. As illustrated inFIG. 1, UE 102 communicates radio signal 107 with eNB 101, radio signal108 with WiFi AP 104, radio signal 109 with BT 105, and receives radiosignal 110 from GPS 106. Radio signal 107 belongs to 3GPP Band 40, radiosignal 108 belongs to one of the fourteen WiFi channels, and radiosignal 109 belongs to one of the seventy-nine Bluetooth channels. Thefrequencies of all those radio signals fall within a range from 2.3 GHzto 2.5 GHz, which may result in significant in-device coexistence (IDC)interference. The problem is more severe around the 2.4 GHz ISM (TheIndustrial, Scientific and Medical) radio frequency band (e.g., rangesfrom 2400-2483.5 MHz), which is used by both the WiFi channels and theBluetooth channels. On the other hand, UE 103 communicates radio signal111 with eNB 101 and does not suffer any in-device coexistenceinterference.

Because UE 102 and UE 103 encounter different IDC interference, it isthus desirable for the network to be able to distinguish UEs with IDCcapability from UEs without IDC capability. In one novel aspect, thenetwork operator allocates a specific set of UE identifies (IDs) (e.g.,International Mobile Equipment Identity - Software Version (IMEI-SV)) tomulti-radio coexisted UEs. In the example of FIG. 1, UE 102 is allocatedwith a UE ID belongs to the specific set of UE IDs, while UE 103 isallocated with a UE ID does not belong to the specific set of UE IDs.Based on the UE ID, for radio resource management (RRM) operations, eNB101 refrains from handing over UE 102 to cells in the ISM bands or nearthe ISM bands when UE 102 stays in RRC_CONNECTED state. On the otherhand, when UE 102 goes to RRC_IDLE state, eNB 101 prioritizes non-ISMbands via RRCConnectionRelease message with redirection parameters.Identifying IDC capability by UE ID is a CN-centric solution, and is abackward compatible solution that is transparent to UEs. However, somespectrum frequencies may be under-utilized. For example, UE 102 may notturn on its WiFi or BT radio transceiver all the time.

For UEs with IDC capability (e.g., LTE radio device coexisted within-device ISM applications), there are three operation scenarios. Afirst scenario is that the LTE UE is conducting voice communication andno in-device ISM application is running. A second scenario is that theLTE UE is conducting voice communication and the in-device ISMapplication is also running. A third scenario is that the LTE UE is idleand the in-device ISM application is running. Meanwhile, the UEperiodically listens to downlink paging channel. Based on the principlesof frequency division multiplexing (FDM) and time division multiplexing(TDM), different UE-centric and eNB-centric solutions are proposed tomitigate IDC interference under different operation scenarios.

In LTE systems, two radio resource control (RRC) states namely RRC_IDLEand RRC_CONNECTED are defined. In the RRC_IDLE state, a UE can receivebroadcast or multicast data, monitors a paging channel to detectincoming calls, performs neighbor cell measurements for cell selectionor reselection, and acquires system-broadcasting information. Mobilityis controlled by the UE in the RRC_IDLE state. In the RRC_CONNECTEDstate, the transfer of unicast data to/from UE, and the transfer ofbroadcast/multicast data to UE can take place. The UE monitors controlchannels associated with the shared data channel to determine scheduleddata, provides channel quality feedback information, performs neighborcell measurements and measurement reporting, and acquiressystem-broadcasting information. Unlike the RRC_IDLE state, mobility andhandovers in the RRC_CONNECTED state are network-controlled and assistedby the UE.

For UE-centric solution, a UE with IDC capability may perform cellselection or reselection to cells in non-ISM frequencies to mitigate IDCinterference without network assistance. FIG. 2 is a flow chart of amethod of performing cell selection or reselection in RRC_IDLE state inaccordance with one novel aspect. In general, a UE equipped with both anLTE radio and a coexisting ISM-band radio is able to detect theactivation of the ISM-band radio (step 201). If the UE is inRRC_CONNECTED state, then the UE goes back to RRC_IDLE state in step202. In RRC_IDLE state, the UE tries to select or reselect to cells innon-ISM frequencies by intentionally de-prioritizing the ISM frequencies(step 203). De-prioritizing ISM frequencies for cell selection orreselection is a UE-centric solution. It is only relevant to UE internaloperation and the network is unaware of the ISM operation in UE. Becausethere is no standard impact, this solution could be applied to LTERel-8/9 UEs. However, there could be some transmission interruption tothe on-going LTE communications when the UE switches from RRC_CONNECTEDstate to RRC_IDLE state.

On the other hand, for LTE network-controlled UE-assisted solutions, theUE can send an indication to the network to report the coexistenceproblems. In one example, the UE indicates the network that coexistenceproblem may become serious on the serving frequency due to increase ofISM traffic. In another example, the UE indicates the network thatcertain of non-serving frequencies are experiencing serious coexistenceproblems (no serious coexistence problems on the serving frequency). Inyet another example, the UE indicates the network that coexistenceproblems may become serious on the non-serving frequencies (no seriouscoexistence problems on the serving frequency). More specifically, a UEwith IDC capability may signal its IDC capability to its serving eNB(static reporting). The UE may also report the activation ordeactivation of its coexisting ISM applications to the serving eNB(semi-static reporting). Furthermore, the UE may report measurementresults to the serving eNB (dynamic reporting). Based on the reportedinformation, the eNB may make certain handover or scheduling decisionsto mitigate IDC interference based on FDM or TDM solutions.

FIG. 3 is a flow chart of a method of signaling in-device coexistence(IDC) from UE perspective in accordance with one novel aspect. In step301, a UE establishes RRC connection with a serving eNB. The UE has anLTE radio module and a coexisting radio device (e.g., an ID device) thatmay introduce interference to the LTE module. For example, the ID devicemay be a WiFi radio or a BT radio that operates in ISM frequencies. Instep 302, the UE signals the existence of its ID device via a UEcapability message. The UE may report its capability information to theserving eNB directly, or report to a mobility management entity (MME)during registration procedure. Later on, the UE signals the activationof ISM band application on the ID device to the eNB (step 303). Finally,the UE measures signal quality (e.g., RSRP/RSRQ of the serving cell) andreports measurement results to the eNB (step 304). The measurementresults may also include signal quality of frequency bands used by thecoexisting radio device.

FIG. 4 is a flow chart of a method of signaling in-device coexistence(IDC) from eNB perspective in accordance with one novel aspect. In step401, an eNB provides communication services to a UE over a serving cell.In step 402, the eNB receives UE capability information indicating IDCcapability of the UE. In step 403, the eNB receives an activationindication of a coexisting radio device of the UE. The eNB may alsoreceive measurement report of the serving cell as well as reports offrequency bands used by the coexisting radio device. Based on thereceived information, the eNB handovers the UE to a cell in anotherfrequency if the serving frequency is near the frequency of thecoexisting radio device (step 404). Finally, in step 405, the servingeNB forwards IDC information to a target eNB to prevent ping-pongeffect. Various embodiments and examples of signaling IDC informationand thereby mitigating IDC interference are now described below withmore details and accompanying drawings.

FIG. 5 illustrates a method of signaling in-device coexistence (IDC) viacapability negotiation in a wireless communication system 500. Wirelesscommunication system 500 comprises a UE501, an eNB502, and a MME503. Instep 511, UE501 and its serving eNB502 performs RRC connectionestablishment procedure (e.g., UE501 in RRC_CONNECTED STATE). In step512, eNB502 transmits a UE capability request to MME503. In response,MME503 transmits a UE capability response to eNB502 in step 513. MME503obtains UE capability information from an earlier registrationprocedure. UE501 is a UE having an LTE radio module and an ID devicethat can introduce IDC interference to the LTE module. In a firstembodiment, a new parameter for indicating the ID device is added in UEcapability information. Whenever UE501 attaches to the network, theexistence of the ID device is indicated via the UE capabilityinformation. This embodiment is not backward compatible because a newASN.1 code-point is needed to support the new parameter.

In a second embodiment, the UE capability information includes thefrequency bands supported by UE501, and the existence of the ID deviceis implicitly indicated by the change of supported frequency bands. Forexample, the UE supported frequency bands originally include Band 40(e.g., 2300-2400 MHz) for LTE TDD mode. In step 514, UE501 turns on itsID device, which operates in ISM frequency band. To mitigate IDCinterference, UE501 performs de-registration procedure with MME503 instep 515. After de-registration, UE501 goes back to RRC IDLE state instep 516. UE501 then registers with the system again and initiates atrack area update (TAU) procedure with MME503 in step 517. During theTAU procedure, UE501 updates its capability to MMS503 indicating thatBand 40 is no longer supported by UE501. By removing Band 40 from thesupported frequency bands, UE501 implicitly signals the MME and eNB theexistence of ISM band application on UE501. This embodiment is backwardcompatible and can be applied in Rel-8/9 LTE UE/eNB. However, it is kindof a dynamic indication and the TAU procedure involves MME operation.

In addition to capability negotiation, a UE can also signal theactivation of its ISM band application by radio resource control (RRC)layer messaging or media access control (MAC) layer control element(CE). In general, the UE can update the activation/deactivation of itsID devices (semi-static reporting) or report the measurement results ofthe frequencies that may be affected by the ID devices (dynamicreporting). More specifically, the UE can report IDC informationrepresented in the form of RRC massage or MAC CE, and the carriedinformation can be measurements based on eNB configuration includingadditional measurement reports for ISM radios. Based on the reportedinformation, the eNB can handover UE to cells in the non-ISM frequencies(FDM solution) or schedule LTE transmission in time domain with care(TDM solution). For example, UE judgment is taken as a baseline approachfor the FDM solution and the UE will trigger IDC indication to itsserving eNB and will indicate which frequencies are usable or unusabledue to IDC interference.

FIG. 6 illustrates a first embodiment of signaling IDC and ISM bandapplication via measurement configuration of an existing event. In theexample of FIG. 6, UE601 is in RRC_CONNECTED state and is served byeNB602 over a frequency band X (step 611). In step 612, UE601 receivesmeasurement configuration (e.g., for an existing event A2 and extendedfor IDC) from eNB602. In step 613, UE601 turns on its ID device runningISM application. Based on the measurement configuration, UE601 measuressignal quality of the serving cell (e.g., frequency band X) as well assignal quality of ISM frequency bands used by the ID device. In step614, UE601 reports measurement results to eNB602. For example, themeasurement report may be triggered by the configured measurement eventA2. It should be noted that other measurement events other than A2 mightalso be applied as well, and the ISM frequency bands measurement resultsmay be piggybacked onto normal measurement report.

FIG. 7 illustrates a second embodiment of signaling ISM and applicationvia measurement configuration of a new IDC event. In the example of FIG.7, UE701 is in RRC_CONNECTED state and is served by eNB702 over afrequency band X (step 711). In step 712, UE701 receives measurementconfiguration (e.g., for a new event IDC) from eNB702. In step 713,UE701 turns on its ID device running ISM application. Based on themeasurement configuration, UE701 measures signal quality of the servingcell (e.g., frequency band X) as well as signal quality of ISM frequencybands used by the ID device. In step 714, UE701 reports measurementresults to eNB702. For example, the measurement report may be triggeredby the configured measurement event IDC. It should be noted that thismethod could be applied in the scenario that LTE signal stronglyinterferes ID devices. In addition, UE701 measures the signal qualityand reports the measurement results to serving eNB702 even if the signalquality of the serving cell is above an s-Measure threshold (e.g., thestop-measure mechanism is disabled). In another embodiment, an IDCthreshold is defined to enable the measurement of the frequency bandsused by ID devices.

Under the dynamic signaling method illustrated in FIGS. 6 and 7, if theinterference situation changes significantly, the UE should send anindication to the network to report the updated interference situation.The triggering condition for sending the indications is configured bythe eNB. This is a non-backward compatible solution because a newreporting procedure or modification to current measurement report whichincludes measurement configuration and report event are required.However, this method provides the most UE information so that the eNBcan manage the UE with the most flexibility to achieve precise controland better spectral utilization.

FIG. 8 illustrates a method of MAC CE-based IDC indication forsemi-static reporting. In the example of FIG. 8, UE801 turns on its IDdevice running ISM application in step 811. In step 812, UE801 transmitsIDC indication information to its serving eNB802. The IDC indicationinformation includes ID device type, ID device traffic pattern, andoptionally UE measurements on ISM bands (e.g., for dynamic reporting).In this semi-static reporting method, the eNB is informed whenever anin-device modem is enabled or disabled. A new reporting procedure isrequired (e.g., MAC CE or RRC). Because the eNB only knows limited IDCindication information, it may result in lower frequency utilization forthe frequency band that may be interfered by the in-device modem ascompared to the dynamic reporting method.

In one advantageous aspect, when a serving eNB handovers a UE to atarget eNB over a non-ISM frequency band to mitigate IDC interference,the target eNB should refrain from handing over the UE back to ISMfrequency band to avoid ping-pong effect. There are two types ofsolutions to avoid ping-pong effect. A first type of solution iseNB-centric solution (e.g., information forwarding among eNBs via X2interface), and a second type of solution is UE-centric solution.

FIG. 9 illustrates one embodiment of eNB-centric solution for avoidingping-pong effect. In the example of FIG. 9, UE901 turns on its ID devicerunning ISM application in step 911. In step 912, UE901 transmits IDCinformation to its serving eNB902. The IDC information may include UEcapability information of its ID device type and ID device trafficpattern, UE measurement configuration, UE measurement results, and UEhandover history information. In step 913, the source eNB902 initiates ahandover procedure by sending a handover preparation information to thetarget eNB903. In addition, eNB902 forwards the IDC information toeNB903. In step 914, eNB903 transmits a handover command back to eNB902,which includes the RRC configurations from the target eNB903. In step915, the source eNB902 transmits a handover message (e.g.,RRCConnectionReconfiguration message in LTE/LTE-A system) to UE901. Uponreceive the handover message, UE901 handovers from source eNB902 totarget eNB903 in step 916. Because the target eNB903 has obtained IDCinformation, it will refrain from handover UE901 back to the sourceeNB902 if UE capability, measurement configuration, or measurementreport indicates IDC interference.

FIG. 10 illustrates one embodiment of UE-centric solution for avoidingping-pong effect. When a UE detects an occurrence of RLF on a servingcell, the UE first switches from RRC_CONNECTED state to RRC_IDLE state.The UE then performs cell reselection to select a new cell. Whenre-establishing RRC connection with the newly selected cell, the UEsends a reestablishment request with an error cause to indicate IDCinterference. As illustrated in FIG. 10, anRRCConnectionReestablishmentRequest 1001 comprises aReestablishmentCause 1002 that includes “IDC failure” error cause 1003.With this error cause, the UE will not be handover from the newlyselected cell back to the original cell.

In one embodiment, the proposed dynamic reporting is coupled with filtermitigation mechanism (e.g., interference cancellation). When an IDdevice is activated, the UE first enables filter mitigation mechanism toalleviate the interference from the ID device. If the residualinterference is still strong, then the UE reports IDC indication to itsserving eNB.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. For example, although an LTE-advancedmobile communication system is exemplified to describe the presentinvention, the present invention can be similarly applied to othermobile communication systems. For example, the IDC interference comesfrom a phenomenon where multiple radio devices co-existing/co-locatingin the same terminal interfere each other. The proposed reportingmethods can be applied to other communication systems that areco-existed with in-device radios. Moreover, the phenomenon may occur inany frequency band employed by multiple radios. Frequency band of TVwhite space is one of the examples. The proposed reporting methods canbe applied to resolve the IDC problem in those frequency bands.Accordingly, various modifications, adaptations, and combinations ofvarious features of the described embodiments can be practiced withoutdeparting from the scope of the invention as set forth in the claims.

What is claimed is:
 1. A method comprising: detecting an activation ofan ISM-band radio transceiver of a user equipment (UE) in a wirelesscommunication system, wherein the UE is equipped with the ISM-band radiotransceiver and a coexisting OFDMA-based radio transceiver; switching toRRC_IDLE state if the UE is in RRC_CONNECTED state upon detecting theactivation of the ISM-band radio transceiver; and reselecting to a cellin non-ISM frequencies if the UE is in RRC_IDLE state, wherein thereselecting is based on prioritizing the non-ISM frequencies forOFDMA-based communications.
 2. The method of claim 1, furthercomprising: detecting an occurrence of radio link failure (RLF) andswitching to RRC_IDLE state from RRC_CONNECTED state before thereselecting; and re-establishing RRC connection with the newlyre-selected cell with a reestablishment cause, wherein thereestablishment cause includes an error cause of in-device coexistence(IDC) interference.
 3. A method comprising: connecting to a serving basestation by a user equipment (UE) in a wireless communication system,wherein the UE is equipped with an OFDMA-based radio module and acoexisting radio device that introduces coexistence interference to theOFDMA-based radio module; performing a registration procedure with thesystem and thereby providing UE capability information containingsupported bands; performing a deregistration procedure with the systemupon detecting an activation of the coexisting radio device, wherein theUE provides updated UE capability information; and reporting in-devicecoexistence (IDC) capability to the serving base station, wherein theexistence of the coexisting radio device is indicated via the updated UEcapability information containing updated supported bands.
 4. The methodof claim 3, wherein the UE capability information comprises a parameterindicating the coexisting radio device.
 5. The method of claim 3,wherein the existence of the coexisting radio device is implicitlyindicated by information of supported bands, wherein the frequency bandsused by the coexisting radio device are excluded.
 6. The method of claim3, further comprising: detecting an activation/deactivation of thecoexisting radio device; reporting the activation/deactivation of thecoexisting radio device to the serving base station.
 7. The method ofclaim 6, wherein the reporting is via a media access control (MAC)control element (CE) indication or a radio resource control (RRC)message.
 8. The method of claim 3, further comprising: measuring signalquality and reporting measurement results to the serving base station,wherein the measurement report includes signal quality of frequencybands used by the coexisting radio device.
 9. The method of claim 8,wherein the reporting is based on the measurement configuration of anevent configured by the serving base station, and wherein themeasurement results of the frequency bands used by the coexisting radiodevice are piggybacked onto normal measurement report.
 10. The method ofclaim 8, wherein the measuring and reporting are based on measurementconfiguration of an IDC event configured by the serving base station.11. The method of claim 8, wherein the measuring is performed when thesignal quality of its serving cell is higher than an s-Measurethreshold.
 12. A method comprising: serving a user equipment (UE) over aserving cell by a serving base station in a wireless communicationsystem; transmitting a UE capability request to the system; receiving UEcapability information that indicates in-device coexistence (IDC)capability of the UE in response to the UE capability request, whereinthe UE capability information contains supported bands; obtainingupdated UE capability information when a coexisting radio device isactivated, wherein the existence of a the coexisting radio device isindicated by the updated UE capability information containing updatedsupported bands; and handing over the UE to a cell in another frequencythat is away from the frequency of the serving cell if the servingfrequency is near the frequency of the coexisting radio device.
 13. Themethod of claim 12, wherein the serving base station receives aparameter in the UE capability information indicating the coexistingradio device.
 14. The method of claim 12, wherein the serving basestation receives information of supported bands, wherein the frequencybands of the coexisting radio device are excluded.
 15. The method ofclaim 12, further comprising: receiving an indication of anactivation/deactivation of the coexisting radio device.
 16. The methodof claim 15, wherein the indication is transmitted via a media accesscontrol (MAC) control element (CE) or a radio resource control (RRC)message.
 17. The method of claim 12, further comprising: receivingchannel quality measurement results reported by the UE, wherein themeasurement report includes signal quality of frequency bands used bythe coexisting radio device.
 18. The method of claim 17, wherein theserving base station configures the measurement of an event, and whereinthe measurement results of the frequency bands used by the coexistingradio device are piggybacked onto the measurement report of theconfigured event.
 19. The method of claim 17, wherein the serving basestation configures the measurement of an IDC event.
 20. The method ofclaim 12, further comprising: forwarding IDC information to a targetbase station, wherein the IDC information comprises at least one of UEcapability information, UE measurement configuration, UE measurementresults, and UE handover history information.